slog-rs

Documentation

Code snippet

``` rust fn main() { // Create a new group of loggers, sharing one drain. let root = root_logger!("version" => VERSION);

// Child loggers clone the `key: values` pairs from their parents.
let _log = child_logger!(root, "child" => 1);

// Closures can be used for values that change at runtime.
// Data captured by the closure needs to be `Send+Sync`.
let counter = Arc::new(AtomicUsize::new(0));
let log = child_logger!(root, "counter" => {
    let counter = counter.clone();
    move || { counter.load(SeqCst)}
});

info!(log, "before-fetch-add"); // counter == 0
counter.fetch_add(1, SeqCst);
info!(log, "after-fetch-add"); // counter == 1

// Drains can be swapped atomically (race-free).
log.set_drain(
    // drains are composable
    drain::filter_level(
        Level::Info,
        drain::stream(
            std::io::stderr(),
            // multiple outputs formats are supported
            format::Json::new(),
            ),
        ),
    );

// Closures can be used for lazy evaluation:
// This `slow_fib` won't be evaluated, as the current drain discards
// "trace" level logging records.
trace!(log, "trace", "lazy-closure" => Box::new(move || slow_fib(40)));

// Loggers are internally atomically reference counted so can be cloned,
// passed between threads and stored without hassle.
let join = thread::spawn({
    let log = log.clone();
    move || {
        info!(log, "subthread", "stage" => "start");
        thread::sleep(Duration::new(1, 0));
        info!(log, "subthread", "stage" => "end");
    }
});

join.join().unwrap();

} ```

See examples/features.rs for full code.

Introduction

Structured, composable logging for Rust. Work in progress, but usable already.

Heavily inspired by [log15] for Go, which I liked so much, that I want it in Rust too.

Read Documentation for details and features.

If you want to say hi, or need help use #dpc gitter.im.

To report a bug or ask for features use github issues.

Building & running

If you need to install Rust (come on, you should have done that long time ago!), use rustup.

In your project

In Cargo.toml:

[dependencies] slog = "*"

In your main.rs:

extern crate slog;